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To obtain the optimal hot deformation process, the rheological and dynamic recrystallization behaviors of A100 steel were researched through isothermal compression tests. Firstly, a Hensel-Spittel constitutive model was established based on the stress–strain curves. Secondly, dynamic recrystallization percentage and grain size models were established to identify the necessary conditions for complete dynamic recrystallization. Finally, microstructural analysis was employed to validate the accuracy of the recrystallization model. The results indicate that the flow stress is highly sensitive to both the strain rate and the temperature, and the HS model demonstrates a high predictive accuracy, with a correlation coefficient of 0.9914. There exists a contradictory relationship between decreasing the average grain size and increasing the recrystallization percentage. The higher the percentage of dynamic recrystallization, the larger the average grain size tends to be. This situation should be avoided when devising the actual processing procedures. The optimal hot working processes for achieving complete dynamic recrystallization and a smaller average grain size are as follows: a strain equal to or greater than 0.6, a temperature between 1193 and 1353 K, and a strain rate between 0.1 and 1 s−1.

Working in a Mexican restaurant during his teenage years, Mark Buchanan discovered his love for jalapeños. Since then he has climbed higher and higher on the Scoville scale.

The application of shape memory alloys is very suitable for developing pipe joints, and Fe-Mn-Si memory alloy pipe joints show great promise. This paper studied the variation rule and microscopic mechanism of the strain recovery rates of Fe-24Mn-6Si-7Cr-3Ni alloy pipe joints made by three different hot working technologies: casting, forging, and rolling. The strain recovery rate of as-cast pipe joints rose monotonously with the increasing thermomechanical training cycle. As-cast pipe joints’ superior shape memory effect mainly came from the large grain size of 662.70 μm and the low density of annealing twin boundaries. On the other hand, the shape memory effects of forging and rolling pipe joints were restricted by the high densities of annealing twin boundaries and grain boundaries, respectively. Although the shape memory effects had a lower upper limit, their strain recovery rates climbed quickly. Following the third annealing, the remaining second-phase particles precipitated according to the ε -martensitic distribution orientation, and this contributed to the shape memory effects of as-cast and forging pipe joints. During adjusting the solution treatment parameters for as-cast pipe joints, it was found that as-cast pipe joints without solution treatment exhibited a notable superiority over the solution-treated ones when less thermomechanical training was performed.

This study investigates the surface characteristics and corrosion behavior of a high-C martensitic stainless steel (AISI 440C) at different stages of its manufacturing process. As a class, these steels prioritize high mechanical properties and wear resistance over superior corrosion resistance. Hot working operations, such as rolling, create a surface oxide scale that must be removed via pickling to restore the material’s inherent corrosion resistance. This process also eliminates the underlying Cr-depleted layer, allowing for the re-establishment of a protective passive film. Using potentiodynamic polarization curves and micrographic analysis, the material’s behavior in different conditions, as-rolled, with a post-heat treatment oxide scale, and in a bare, oxide-free state, has been assessed. The results showed that the material lacks stable passive behavior under all conditions. The as-rolled and heat-treated conditions both exhibited active behavior and formed thick, non-adherent corrosion products. The oxide layer formed after heat treatment performed the worst, showing a significant increase in corrosion current density. These findings confirm the material’s susceptibility to corrosion in Cl− ion-rich environments, highlighting the need for limited storage in such conditions and rapid pickling after thermal processing to mitigate surface damage.

The dynamic recrystallization (DRX) mechanism of as-cast nickel base superalloy N10276 during primary hot working was investigated by compression tests at temperatures of 1000–1200 °C and strain rates between 0.01 and 10 s −1 . Optical microscopy, scanning electron microscopy, electron backscattered diffraction technique and transmission electron microscopy were used to characterize the evolution of microstructure. At higher deformation temperature or lower strain rate, the true stress–true strain curves exhibit the characteristic of a peak stress followed by a steady state flow stress under large strains, confirming the occurrence of DRX. The degree of DRX increases with elevating deformation temperature. With the progress of DRX, low angle grain boundaries gradually decrease, while high angle grain boundaries increase continuously. Microstructure studies have shown that discontinuous dynamic recrystallization is the main recrystallization mechanism. Since there are few original grain boundaries and twin boundaries, and lack of second phase particles for particle stimulated nucleation, geometrically necessary boundaries are formed as supplementary nucleation sites through sub-grain boundary rotation and deformation twin boundaries. The annealing twins dominated by Σ3 grain boundaries are generated in large quantities during the growth of recrystallized grains.

The dynamic recrystallization (DRX) behavior of 47Zr-45Ti-5Al-3V alloy was studied by using the experiment and numerical simulation method based on DEFORM-3D software and cellular automata (CA) over a range of deformation temperatures (850 to 1050 °C) and strain rates (10−3 to 100 s−1). The results reveal that the DRX behavior of 47Zr-45Ti-5Al-3V alloy strongly depends on hot-working parameters. With rising deformation temperature (T) and decreasing strain rate (ε˙), the grain size (dDRX) and volume fraction (XDRX) of DRX dramatically boost. The kinetics models of the dDRX and XDRX of DRX grains were established. According to the developed kinetics models for DRX of 47Zr-45Ti-5Al-3V alloy, the distributions of the dDRX and XDRX for DRX grains were predicted by DEFORM-3D. DRX microstructure evolution is simulated by CA. The correlation of the kinetics model is verified by comparing the dDRX and XDRX between the experimental and finite element simulation (FEM) results. The nucleation and growth of dynamic recrystallization grains in 47Zr-45Ti-5Al-3V alloy during hot-working can be simulated accurately by CA simulation, comparing with FEM.

Working in a Mexican restaurant during his teenage years, Mark Buchanan discovered his love for jalapeños. Since then he has climbed higher and higher on the Scoville scale.

The high nitrogen austenitic stainless steel is widely used as power generation and geological exploration equipment materials because of its excellent strength, corrosion resistance and non-magnetic. In this paper, the mechanical behavior and microstructure evolution of P550 steel in the range of 900 °C–1200 °C and 0.001–10 s −1 deformation conditions were studied by physical and heat treatment simulations, metallographic observations and thermal processing maps. The results showed that the flow curves quickly reach the peak and then soften to a steady state, which indicates dynamic recrystallization (DRX) behavior. DRX is easy to occur when the deformation temperature is above 1080 °C. The activation energy of the forged P550 stainless steel was calculated as 519 kJ mol −1 . There is a positive correlation between the peak stress, DRX critical stress, strain and Z value of the tested steel. The instability of the tested steel is easy to produce in the high strain rate region and low temperature region during hot working. Crack germinates and expands preferentially at the ‘necklace structure’ of inadequate dynamic recrystallization. Under the deformation state of 0.001 s −1 , coarse crystals and mixed crystals are easily emerged during subsequent heat treatment. Combining the hot working map, the maximum deformation resistance and the grain evolution behavior during hot working and heat treatment, the suggested working window is T = 1020 °C–1200 °C and έ = 0.01–1 s −1 .

Fe40Mn20Cr20Ni20 medium-entropy alloy (MEA) has a single-phase crystal structure with high strength and good ductility at room temperature. It is important to study the hot deformation behavior for this alloy at a partially recrystallized state for possible high-temperature applications. In this investigation, the tensile tests were conducted on sheet materials treated via cold rolling combined with annealing at strain rates of 1 × 10−3–1 × 10−1 s−1 and deformation temperatures of 573–873 K. And the hyperbolic sine model was used to study the relationship between the peak stress, deformation energy storage and Zener–Hollomon parameter (Z parameter) of Fe40Mn20Cr20Ni20 medium-entropy alloys under high-temperature tension. According to the Arrhenius-type model, the constitutive equation of the alloys based on the flow stress was constructed, and the deformation activation energy and material parameters under different strain conditions were obtained. Based on the power dissipation theory and the instability criterion of the dynamic material model, the power dissipation diagram and the instability diagram were constructed, and the hot working map with a strain of 0.1 was obtained. The results show that the hyperbolic sine relation between the peak stress and Zener–Hollomon parameters can be well satisfied, and the deformation activation energy Q is 242.51 KJ/mol. Finally, the excellent thermo-mechanical processing range is calculated based on the hot working map. The flow instability region is 620–700 K and the strain rate is 2 × 10−3–4 × 10−3 s−1, as well as in the range of 787–873 K and 2 × 10−3–2.73 × 10−2 s−1. The optimum thermo-mechanical window is 850–873 K, ε˙ = 1 × 10−3–2 × 10−3 s−1.

Silver products with high relief have become popular in the silver decoration industry. However, it is difficult to obtain these products through conventional processing at ambient temperature. The aim of this work is to solve this problem by increasing the deformation temperature. Detailed studies were conducted on the evolution of microstructure characteristics in bulk high-purity silver by electron backscatter diffraction (EBSD) to achieve high-relief applications at elevated temperatures. The high temperature sample is mainly composed of recrystallized and substructured grains, exhibiting a more stable state than the ambient temperature sample. More than 70% annealing twins are observed in the hot-working sample. They are characterized by the amount of Σ3n-type triple grain boundary junctions within large grain clusters formed by multiple twinning. These particular boundaries improve the intergranular corrosion resistance and degradation, which is significantly essential for high-purity silver jewelry exposed to sweat and air. The closed multi-coining processes at different temperatures were conducted subsequently. The performance of workpieces demonstrates that increasing the deformation temperature is a viable alternative for producing durable high-relief silver products.